750 THE VOYAGE OF H.M.S. CHALLENGER. 



in length the thii-d, fourth, and fifth joints united; it has some setae along the front 

 margin, and a short apical seta on the hinder ; the short second joint has two small 

 spines or setules on the hind margin ; the third joint is longer than the wrist, which it 

 overlaps, subequal to the hand, its free front margin very short, the hind margin 

 straight, carrying three spines, a little furred below ; the rounded apical margia carrying 

 a group of spines ; the wrist triangular, distally cup-like, with an apical group of spines 

 behind ; the hand with a convex front margin much longer than the hind margin, which 

 carries short stout spines at two points, and a third group at the commencement of the 

 broad, oblique, finely pectinate palm, which is fringed with a few submarginal setae ; the 

 finger is broad almost to the end, which is sharp, closing down upon the palmar spines ; 

 it has two dorsal cilia near the centre, the dorsal margin being much more convex than 

 the finely pectinate inner margin. 



Second GnatJwpods much larger than the first. Side-plates large, almost semi- 

 circular. The branchial vesicles sac-like, much smaller than the side-plate. Marsupial 

 plates very large, very broad, and very thin. First joint reaching beyond the side-plate, 

 a little longer than the hand, distally widened and curved slightly forwards, with some 

 spines on the hind margin; the second joint short, with one or two setules on the hind 

 margin ; the third joint short, with no free front margin, the hinder apically acute ; the 

 wrist short, cup-like, with a group of spines on the ciliated hinder apex ; the hand large, 

 not twice as long as broad, with a few spines on the basal half of the front margin ; the 

 hind margin continuous with the convex palm, which is but slightly toothed or indented, 

 the chief prominence being a small one near the hinge of the finger ; the finger is very 

 long and broad, its apex passing beyond the palmar spines and resting against the surface 

 of the hand just within the margin ; its inner edge is smooth, with one or two cilia and 

 a small decurrent tooth preceding the sharp apex. 



First Peraiopods. — Side-plates very broad, rather broader below than above, the hind 

 margin longer than the front, the lower margin convex. Branchial vesicles pear-shaped, 

 nearly as long but not nearly so wide as the side-plates. Marsupial plates smaller than 

 the preceding pair. The first joint of the limb scarcely reaching beyond the side-plate, 

 with spines along the front margin and lower part of the hinder ; as in the preceding 

 pair, this joint is distally lobed in front on two edges ; the second joint is short, with a 

 spine or two on the hind margin ; the third is longer than the fourth, about equal to the 

 fifth, with five spines on the front margin, and a group on its decurrent ajDex, some 

 spinules in front and an apical spine ; the fourth joint has spines at five points of the 

 straight hind margin ; the fifth joint is curved, and carries some seven groups of spines 

 on the concave hind margin, the accessory thread in these and many of those previously 

 mentioned arising at the centre of the spine ; there are spinules or setules at four points 

 of the hind margin ; the finger is short and curved, little more than half the length of 

 the fifth joint. 



